Restoring default toolbar layout in Blender 2.81
From the file dialog

When you are in the Open File dialog, click the Settings icon in the top right.

Then deselect Load UI



Setting default behaviour

You can also change the default behaviour by changing your preferences.

Go to Edit → Preferences → Save &amp; Load and uncheck Load UI



Be warned that this might be equally frustrating if your startup file does not contain all the views you would expect.